Dynamo-electric machine and system of control therefor



i R. E. HELLMUNE. DYNAMO ELECTRC MACHNE AND SYSTEM 0F CONTROL-THEREFOR.

APPLICATIONYFILED NDV. I9, 19|?.

Patented May 24, 1921.

4 SHEE -SHEET l.

MWL fc ATTORNEY myENTR He//mz/na.

l V R. E. HLLMUND.

YNMO ELECTRIC MACHlNE AND SYSTEM 0F CONTROL' THREFOH. APPUCTION FILED N0l.\9| 1917.4 1,379,406, Patented May 24,1921.

4 SHEETS-SHEET 2.

INVENTOR Hwa/ff, /f//m/d c i vBY /VL'HQUQD-tf vec l ATTORNEY R. E. HELLMUND.

DYNAMO ELECTRIC MACHINE AND SYSTEM 0F CONTROL THEREFOR.

APPLICATION F1151) 110119. 1911.

1,379,406. .Patented may 24,1921.

4 SHEETS-SHEET 3.

' l i 1 l l 1 .1. l 1 1 I l l 1 l 1 o e o 69 69 l iHbMHqQ: I l I 1 l 1 l i 1 l i I BYl TmRNEY i R. E'. HELLMUND.

DYNAMO ELECTRIC MACHINE AND SYSTEM OF CONTROL THEREFOR.

.APPLICATION FILED IIo-v4 I9, `I9I.1.

1,37 9 ,406`v Patented May 24,1921.

.4 SHEETS-SHEET 4.

` wITNEssEs; INVENTOR ATTORNEY umTian STATES PATENT OFFICE.

RUDOLF E. HELLMUND, or sWrssvaLE, PENNSYLVANIA, nssIeNoR To WESTING- A HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPQRA'TION 0F. PENN SYLVANI'A.

nYNATro-nLEcTnTo MACTTINE AND sir-STEM or CONTROL THEREFOR.

To all whom t may concern:

Be it knoyvn that I, RUDOLF E. HELL- MUND, a citizwen of the German Empire, and a resident of Swissvale, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Dynamo-Electric Machines and Systems of Control Therefor, of Whichthe following is a specification.

My invention relates to dynamo-electric machines and to systems ofcontrol therefor and especially vto single-phase4 commutator motors ofthe doubly-fed y,or transformerconduction type.

It is a Well-known fact that the provision of an inducing field Winding, having its magnetizing axis in substantial alinement with the-.electrical armature-winding position Vthat corresponds to the armature brushes of a. single-phase commutator motor, for ythe most part neutralizesthe cross-magnctizing action o f the armature-Winding turns. In addition, the inducingfield Winding sets up a cross flux, shifted about 90o in time against the impressed voltage of the inducing field` Winding, thus preventing injurioussparlting by reason of the fact that the electromotive force induced in the armature turns that are short-circuited by the brushes by the transformer action of the exciting field flux is substantially in timephase opposition to the electromotive force that is induced by rotation .of such shortcircuited armature turns through the fluX created by the inducing field Winding.

llhilethe inducing field Winding, broadly considered, produces the above-mentioned neutralizing action, it is found, in actual operation that, when doubly-fed or transformer-conduction motors are running at a relatively 'low speed, poor commutating conditions obtain, since, by reason ofthe customary practice of making the field-form of the inducingffieldWinding and of the demagnetizing armature ampere-turns substantially alike, the compensating or neutralizing voltageproduced by the inducing field Winding is, in reality, out of phase with the resultant electromotive force that is set up Within the short-circuited,armature- Winlding turns bythe transformer action of the exciting fieldflux and by the small rotational reactance voltage. Furthermore,

Specification of Letters Patent. Y Patented lua-y 24, 1921. Application led November 19, 1911*?. Serial No. 202,700.

yvhena motor of the type underconsideration is operating at lrelatively`high speeds, the rotational reactancevoltage thatisselfinduced in the short-circuited armature turns, Which then Aattainsa relatively high value, in combination AWith the vshort-circuit or transformer-action voltage, produces a resultant voltage Which is again out of phase with the compensating voltage that is induced by the customary inducing field Winding. This is explained more in "detail in a series of articles entitled uSingle-phase commutator motors in the Electric J carnal for 1912 by E. Hellmund and P. Smith I It is the object of my present invention, therefore, to provide a novel inducing-field- Wlnding arrangement rvhereby the' abovementioned out-of-phase relations'of the armature demagnetizing voltage and theneutralizing voltagefef ythe inducing field Winding shall be" eliminated," and "substantial time-phase vopposition of the two-"voltages shall obtain over a Wide range of -speed,

whereby continually satisfactory commutating` conditions may besecured. by

More specifically stated, it is the object of my invention to provide a s'inglc'eV-'ph'as'ecommutator motor With'a double or 'plural-section inducing field Winding, the "arrange- -ment of parts being suchgthat bue' off the sections, acting' alone, produces afield-form somewhat fia-tterthan that ofthe'iai'mature deniagnetizing turns, While the combinedfor superimposed effect of the inducing-field- Winding sections Will provide a morepointed or peaked field-form than 'such armature turns. In this Way,l l have found'tliatkthe compensatingy voltage and the. armature-re actance voltage that it is ,desired to neutralize, are maintained in substantial"time-phase opposition throughout Wide speed range of the transformerconduction motor.

My invention best be'understood by` reference "to the accompanyingdrawing, wherein Figure l is a d:llaagvgrzimnnatic4 view of la single-phase commutatorniotor together `With a control system lembodying'theV principles of the present invention; Fig. Q'to Fig. inclusive, are Jsimplified diagrammatic views of main-circuit connections that may be emnloved to achieve the above-mentioned advantages of my invention gand Figs.

8 to 10 are vector-diagrams illustrating the` working principles of the invention.

Referring to Fig. 1 of the drawing, the system shown comprises a single-phase coinmutator motor having an armature A, of the well-known c ommutator type; a main or exciting field winding F and an inducing or compensating field winding that embodies two sections C1 and G2. The motor is energized from any suitable source, such as the secondary winding T2 of an appropriate transformer, and also provide a plurality of unit switches 1 to 11, inclusive, that are electrically energized in the desired sequence from a battery B, or the like, in accordance with the movements of a multi-position master controller MC. Preferably, a pre- Y ventive coil 12, or the equivalent, is provided, in accordance with a familiar practice, to prevent the shortscircuit of portions of the transformer winding during the operation of the motor.

The inducingeiield-winding section C1 is shown as wound around a laminated polar projection 16, or the equivalent, that is provided, in the end-portion adjacent to the armature, with a plurality of longitudinally-extending slots, whereby an intermediate arm or'small polar projection 17 is obtained, upon which the remaining inducing-field-winding section C2 is wound, being connected in series relation with the chief inducing-iield-winding section C1.

The illustrated design and arrangement of parts is provided to produce a relatively flat field-form if the iield-winding-section C1 alone is employed, whereas the combined use of the sections C1 and C2 will produce a rather peaked or pointed field form, as will be understood from the ilustrated location of the section C2, as well as from the subsequent explanation of Figs. 8 to 10. However, it will be appreciated that any other suitable construction for providing the desired combination or superimposition of field-forms may be utilized within the spirit of the present invention: in actual. practice, I employ the distributed type of stator windings that is customary in singie-phase commutator motors.

The armature A is provided with two sets of brushes 18 and 19 that are spaced apart `by a distance corresponding to 180 electrical degrees, and the axis of the inducing polar proyection 16, including the smaller polar pro] ection 17, isr shown as located substantially in alinement with the armature brushes 18 and 19, as is customary. The main or. exciting field winding F is wound lupon a polar projection 20, or the equivalent, the magnetizing axis of which is shown as located substantially at right angles to the line of the armature brushes, as is usual practice.

Assuming that it is desired to effect acceleration of the illustrated motor, the master controller MG may be actuated to its initial position a, whereupon one circuitis established from the positive terminal of the battery B, through conductor 25, control fingers 26 and 27, which are bridged by contact segment 28 of the master controller, conductor 29, and the actuating coil of the switch 11, to ground or other suitable return conductor, whence circuit is completed to the negative terminal of the battery B.

The control lingers 30, 31 and 32 of the master controller are also energized in position a thereof, whereby the switches 4, 1 and 5 are likewise closed.

The initial main-circuit connections are i ther main circuit is established from an,

other intermediate transformer-tap through conductor 44, switch 4 and conductor 45 to the junction-point of the armature A with the exciting field winding F. vThe starting main-circuit connections, corresponding to position l` of the master controller, are illustrated in a simplified manner in Fig. 2, whereby it will be observed that, initially, the entire inducing field winding and the exciting eld winding are connected in series relation with the armature A, which is close-circuited through a relatively small outer section of the transformer winding, the armature connections being made in such manner that a reversed voltage is applied from the outer transformen section to the armature terminals. The motor is thus started in accordance with the familiar reversed doubly-fed or transformer-conduction connection.

It has been found that the circuit inclusion of the small inducing-field-winding section C2 affords advantageous operating conditions at the moment of starting, and, consequently, the section C2 is initially employed but is excluded from circuit as soon as the master controller is moved to its second position 5, whereby the low-speed op erating range of the' motor is, in reality, begun, using the chief inducing-field-winding section C1 alone.

Such movement of the master controller to its position effects the energization of new control lingers 46 and 47, while the control finger 27 becomes disengaged from the Contact segment 28. In thisr way, switches 10 and 2 are closed, while switch 11 is opened. Consequently, an intermediate point 49 in the left-hand half of the transformer winding T2 'is connected, through tion connection is Vthus established, the in-4 ducing-field-winding section. Cl Ybeing directly connectedacrossa small portion of the transformer winding T2, while lthe smaller inducing-ieldwinding section G2 is entirelyexcluded from circuit, as illustrated in Fig. 3. A

Upon actuation of the master -controller to position c, control finger BObecomes disengaged from contact segment 28, whereby switch 4 is opened `to remove the initial reversed transformer-conduction type of connection `from rthe armature A and complete a straight transformer-'conduction connection, as illustrated in Fig. 4.

In position d', the contact'segment-28 engages control finger 51 to close the switch 6, while the switch 5 is opened by .reason of the vdenergization of'its corresponding control finger 32. Consequently, a new circuit is `established from'a `-tap-point 52 in the right-hand half of the transformer winding, through conductor 53, switch 6, conductor 54, the 'left-hand section' of vthe preventive coil 12, and thence, throughfconductors 39 and 38, vto the armature A, as previously described. In this way, an increased voltage from the transformer winding T2 is conductively impressed upon the armature brushes, although the value of the increased voltage step is reduced by the interposition of a section ofthe preventive coil 12. The simplified connections, corresponding to position d, are shown in Fig. 5.

In position e, control finger 55 is energized from the contact segment 28, whereby the switch 8 is Closed to short-circuit the active portion'of the preventive device 12 and thus 'effect the impression of a certain voltage increase upon the armature terminals to further accelerate the motor.

Position f of the master controller effects the energization of a new control finger 56 to close switch 7 and the denergization of control finger 51 to open switch 6. Consequently, a new main circuit is completed from 'the right-hand terminal of the transformer windind T2 `through switch 7, the right-hand sectlon of the preventive coil 12 and thence, through switch 8 and conductor 38 to the armature. tions,analogous to those effectedin position d of the master controller and illustrated in Fig. 5, are thus produced to impress a further step of voltage upon the armature terminals. J f y A In position g, a new control finger 57 is energized to close the switch 9, whereby the field winding F. The' sections A set of connecactive section of the preventive coil l2 is short-circuited and the armature -voltage is further increased.

By this time, the Vflat field-form Vproduced by `vthe inducing-field-winding section C1 alone has about reached the Alimit of its usefulness in preventing phase difference .be-

tween -the compensating field voltage and the armature-reactance voltage, and, consequently, lthe change to lthe use of Vboth inducing-field-winding sections C1 and C2, to produce the desired phase relations under high-speed operation, is effected, lbeginning with position z, of the master controller. In this position, control finger V58 is energized from the contact segment.l 28, whereby switch 3 is closed t0 establish a Inew main circuit from van intermediate transformer tap-point 59, through conductor 60, switch 3, and conductor 61, to the inner terminal ofthe small inducing-field-.winding section C2, as illustrated in Fig. 6, wherein the inducing-field-winding sections C1 and C2 are connected across contiguous portions of the transformer winding, and a predetermined effect upon the inducing iield-form is produced, dependent upon the value of voltagethat is impressed upon the section C2 from the transformer winding T2.

Infthe final master-controller position z', control finger 27 is again energized, while control :fingers 46 and 47 are denergized. -n this way, switch-11 is againrclosed, while switches 10 and 2 are opened. The substitution of switch 11 for switch 10 changes the connection of the lower eXcitingfficld-winding terminal froma pointy intermediate the inducing-field-winding sections C1 and C2 tothe inner terminal of the small section C2, while the .opening of switch 2 rremoves the connection between the transformer and the j unction-oint of the inducing-fieldwinding 1 and C2,which are thus included in a straight series circuit across. a predeterfmined portion of the transformer winding T2, as illustrated in Fig. 7. The final circuit arrangement just recited produces the desired pointed or peaked effect in the inducing field-winding field-form, whereby the previously-mentioned desired correction of phase relations is produced under highspeed operating conditions of thev motor.

The influence of the changed field form upon the phase relation of the voltages in the -short-circuited armature coil may be further explained Vin connection with Figs. 80; to 10c. 'Figs 8a to 8c illustrate the familiar case, in

which the field forms of the armature and that of the inducing field winding are alike.

yIt is assumed that lthe armature conductors 63, 64 and 65 of an inducing-field-winding pole are, as usual, evenly distributed between i the neutral points of the inducing` field winding indicated by dotted lines. The'conductors 63, locatedin the neutral 'of the main field, are parts of the coils short-circuited by the brushes and thus they carry no working currents. Thelatter, flowing in the remaining conductors 64 and 65, tend to set up an armature cross field as shown by the step form in Fig. 8b. If'now the inducing field winding is arranged as also shown inFig. 8a, with coils 71 Aand 7 2 distributed the same as the active armature conductors, it is evident that these coils will produce the same field form.

Referring now to the vector diagram of Fig. 8c, we yhave an armature-circuit voltage Ea. and a current Ia lagging the usual angle G) behind the voltage in time. The inducingfield-winding current I0 is, with regard to its magnet'izing effect, substantially in opposition to Ia, but sufficiently shifted to give, when vectorially combined w'ithIa, av vector cpa, representing the resultant magnetizing effect and, therefore, also the fiux in the teeth a al, which are under the influence of all conductors of both windings. rIhe teeth b b1, are under the influence of half the turns of each winding; thustheir flux ob may be represented by a vector cpb, obtained by combining the vectors (-)Ia and (QIC. The flux interlinking with the inducing field coils 71 is the same as cpa. The flux interlinking with coils 72 is the sum of cpa and cpb as shown by vector o2. `The flux cp, interlinking with the turns 71 induces a counter E. M. F., E1 therein, lagging QOObehind the flux; similarly Q2 induces E2 in coils 72. The sum, -E0, of E1 and E2 gives the total counter electro-motive force of the inducing field winding and must be e ual and opposite to the impressed voltage c. Since the latter is taken from the same transformer as Ea, the two must be in line with each other, as

shown.

With regard to the commutating voltages, it is known that the pulsations of the exciting flux induce a voltage ep at right angles to the current Ia, and that the reactance voltage e1r is in phase with Ia. The two combine to produce es, while the inducing fieldflux cp, in the commutating zone induces Vby rotation a voltage ec. With thel phase angle shown and the reactance voltage e1r being assumed about half as large as the pulsating voltage ep, it follows that ec and es are equal and opposite to each other. We thus have ideal neutralizing conditions under the assumption made and applying to mediumspeed operation. It is at once evident, however, that with low-speed operation, giving small values for the reactance voltage, as, Yfor instance, indicated by vector er, an inducing-field voltage of the phase ec can never give full neutralization of es. Similarly, at high-speed operation, giving large reactance voltages as, for instance, @"r, itis impossible for a voltage ec to neutralize e`s.

Figs. 9a to 90 demonstrate, however, that under such high-speed conditions, with a large value of er, ideal compensation is `possible, if the inducing field is chosen more peaked than the armature field.` Y FigQQ shows thepnew windingrarrangement, with a single turn 72 in the outer inducing fieldwinding slots and three turns 71 in the inner slots. In Fig. 9b the armature field form isl shown as in Fig. 80;, but the inducing field form, indicated by the dotted line, is more peaked in the middle, with the new arrangement. The vector diagram is derived thesame as Fig. 8c. The flux @a is again the resultant of Ia and I0, since it is induced by the full number of turns. It is to bevnoted, however, that the flux cpb in the teeth b b1, is induced by one-half the armature ampereturns @Het and one-quarter the inducing, field turns (@Ic; the twocombine to produce pb,which is,in contra-distinction to Fig. 80,'out of phase with cpa. l,The fiuX 91 interlinking with coils 71 is again the same as cpa, while 92 is .again found as the geometrical sum of oa andqob. In deriving the voltages E1 and E2 at right angles to 91 and c2, the fact that the inner coils 72 have three times the turns of the outer coil 71 has been considered. Aninspection of the vectors el., ep, and es and ec, the latter being in phase with cpa, shows that ideal neutralization is obtained inspite of the large value of e, caused by the highspeed operation.

Fig. 10c shows that similarly ,it is possible to obtain good results with small values of er incident to low speed operation, if the inducing field winding` is arranged as in Fig. 10a to give a flat field form, as illustrated'in ing. 10b. f Y

While rather simple assumptions have been made for the purpose of illustration, the general tendency applies to the practical casey having a larger number of slots. It is thus evident that good all-around conditions can be obtained by using a flat inducing field form for low speed and introducing means for modifying the field form to be' more peaked at higher speeds, as disclosed in connection with Fig. 1.

I do not wish to be restricted tothe specific circuit connections or arrangement of. parts herein set forth, as various modifications thereof may be made without departing'from the spirit and scope of my invention. I desire, therefore, that only such limitations shall be imposed as are indicated in the a pended claims.

I c aim as my invention:

1. The method of operating a single phase commutator machine for the prevention of sparking, which consists in producing, in., the brush axis at the instant of starting, a field fiuX having a pointed field-form, and in producing, in the brush axis during lowspeed running conditions, a field flux having a less pointed field-form.

ioo

2. The method of operating a single phase commutator machine so as to eliminate sparking, which consists in producing a compensating eld flux having a flat field-form, during relatively low-speed operation, and in producing a compensating field flux having a pointed field-form, during relatively high-speed operation.

3. The combination With a single-phase commutator machine having an inducing eld-Winding, of means for manipulating the connections of said inducing ield Winding to provide a field-form that is flatter than that of the demagnetizing armature turns under certain speed conditions of the machine and more pointed under other speed conditions.

4. The combination With a single-phase commutator motor having an inducing field- Winding, of means for manipulating the connections of said inducing field Winding to provide a field-form that is flatter than that of the cross-magnetizing armature turns under certain low-speed conditions of the motor and more pointed under high-speed conn ditions.

5. The method of operating a single-phase commutator motor having a plurality of inducing-field-Winding sections having diii'erent positions in space around the circumference of the field member, which consists in connecting one of asid sections in circuit during certain low-speed motor operation and in connecting all of said sections in circuit during high-speed motor operation.

6. The combination with a single-phase commutator motor having a plurality of inducing-ield-Winding sections that are respectively adapted to produce a relatively flat field-form and a pointed field-form, of means for connecting the flat-ield-form section in circuit alone during a certain speed range and for connecting both sections in circuit during another speed range to improve commutating conditions.

7. The combination With a single-phase commutator motor having a plurality of inducing-lield-Winding sections that are respectively adapted to produce a relatively flat ield-form and a pointed field-form, of means for connecting said sections to produce the flat field-form under certain lowspeed motor operation and to superimpose the pointed field-form upon the flat fieldorm under high-speed motor operation.

8. A single-phase commutator machine having a plurality of inducing-ield-Winding sections, said sections being diierently distributed around the circumference of the field member, and means for connecting one of said sections in circuit during a certain condition of machine operation and for connecting all of said sections in circuit during a different condition of machine operation.

9. The method of operating a single-phase motor comprising armature Working conductors and exciting conductors and a ield Winding in an axis different from the exciting axis that consists in localizing the flux produced by said field Winding under certain operating conditions and distributing such iiux over a Wider area under other operating conditions.

In testimony whereof, I have hereunto subcribed my name this 31st day vof Oct., 191 Y RUDOLF E. HELLMUND. 

